A Mixed EWMA-CUSUM Control Chart for Weibull-Distributed Quality Characteristics

The control charts have been widely used for process monitoring. Shewhart control chart has ability to detect large disturbances in the process. The EWMA and CUSUM charts have ability to detect a small change in the manufacturing process. In this paper, we will design a mixed EWMA-CUSUM control chart for Weibull-distributed quality characteristics. The Weibull distribution is one of the most popular distributions used to model failure mechanism because of flexible selection of shape and scale parameters. A Monte Carlo simulation is developed to assess the average run lengths for in-control and out-of-control process. The comparison revealed that the proposed mixed chart is more sensitive to detect a small shift in the process. Copyright (C) 2016 John Wiley & Sons, Ltd.